Review Question - QID 219900

The patient has a bony mallet injury that involves nearly 50% of the intra-articular surface and volar subluxation of the distal phalanx. Unstable bony mallet injuries that demonstrate volar subluxation should be fixed operatively.

Mallet finger injuries result from a disruption of the terminal extensor tendon distal to the distal interphalangeal (DIP) joint. The injuries are usually caused by a traumatic impaction blow (i.e. sudden forced flexion) to the tip of a finger in the extended position. Clinically, the affected finger shows the distal phalanx resting at ~45° of flexion with a lack of active DIP extension. Treatment is usually extension splinting of the DIP joint for 6-8 weeks in the presence of a bony mallet injury, with purely tendinous injuries often treated for 10-12 weeks. Surgical management, however, is indicated in unstable patterns of injury, such as those exhibiting greater than 50% intra-articular surface involvement that leads to volar subluxation of the distal phalanx, as well as in chronic injuries or those with significant concomitant arthritis.

Avery et al. provide a review of sports-related wrist and hand injuries. The authors note that conservative treatment with extension splinting of the DIP joint is appropriate for almost all mallet fingers, including those with bony fragments, as long as there is no significant joint subluxation. They conclude that treatment in these instances involves full-time DIP splinting with the PIP joint free for 6 weeks around the clock, oftentimes with an additional 6 weeks of nighttime splinting.

Gruber et al. provide a prospective randomized controlled trial comparing night splinting with no splinting after treatment of mallet finger. The authors included 51 patients, 41 of which were available at final follow-up. They found that there were no differences in the degree of extensor lag, disability, or treatment satisfaction between patients who did and did not use night splints. They concluded that supplemental night splinting does not improve the outcome of mallet fingers in terms of extensor lag, disability, or satisfaction with treatment and that patients with worse initial extensor lags should expect worse final lags, with residual lags of 20° or greater being common despite adequate treatment.

Figures A and B demonstrate PA and lateral radiographs of a small finger bony mallet injury comprising at least 50% of the intra-articular surface of the DIPJ and obvious volar subluxation of the distal phalanx.

Incorrect Answers:
Answer 1: Allowing the patient to continue playing with a cast followed by intermittent splinting would be incomplete and inappropriate treatment of his unstable injury pattern.
Answer 3: DIPJ fusion is reserved for failed treatment in chronic injuries or those with significant concomitant arthritis.
Answer 4: Fragment excision with tendon advancement would lead to poor function and hyperextension deformity and is not an appropriate treatment method for this competitive athlete.
Answer 5: Extended full-time extension splinting can be used for purely tendonous injuries; however, bony mallets are typically treated with full-time splinting for 6-8 weeks. Though additional night-time only splinting can be added, the literature has not shown added benefit in terms of the degree of residual extensor lag, disability, or patient satisfaction.